果园生草对^15N利用及土壤累积的影响

EFFECTS OF INTERPLANTING GRASS ON UTILIZATION,LOSS AND ACCUMULATION OF ^(15)N IN APPLE ORCHARD

以2 a生红富士/平邑甜茶为试材,采用15N同位素示踪技术,研究了种植3种牧草(白三叶、鼠茅草和黑麦草)对苹果植株生长,氮素利用、损失及其在0~60 cm土层残留情况的影响。结果表明:与单作苹果相比,生草栽培后苹果植株总鲜重、新梢粗度、新梢长度及根冠比皆成增加的趋势;苹果植株根长、根长密度及根表面积均以种植白三叶处理最大,其次为种植鼠茅草,最低的为单作苹果;不同处理间氮素利用率差异显著,种植白三叶后苹果植株氮素利用率最高,种植鼠茅草次之,单作苹果最低;生草栽培后15N残留主要集中在0~20 cm土层,且其15N残留量显著高于单作苹果。而在20~40 cm及40~60 cm土层15N残留量则以单作苹果最高,种植黑麦草次之,最低的为种植白三叶;生草栽培后氮素损失率为单作苹果>种植黑麦草>种植鼠茅草>种植白三叶。表明种植白三叶、鼠茅草及黑麦草在促进苹果植株氮素利用的同时,也一定程度上减弱了土壤氮素的损失。

A field experiment was carried out of interplanting forage grasses （ Trifolium repens Linn., Vulpia myuros C. and Lolium perenne L. ） in a two-year old ＇Fuji＇ apple （M. domestica Borkh. cv. Red Fuji/Malus hupehensis Rehd. ） orchard to explore effects of grass interplantation on growth of the apple trees, and utilization, loss and residue of nitrogen in the 0 -60 cm soil layer of the orchard, using the ^15N-labeled tracer method. Results show that compared with the apple trees in the plot without grasses interplanted, the trees in the plot with grasses interplanted were found to have an increasing trend in total fresh weight of a plant, thickness and length of new shoots and root-shoot ratio; The effect on root length, roots length density and roots surface area of apple trees was the most significant in the plot interplanted with Trifolium repens Linn., which was followed by the plot with Vulpia myuros C. and the plot with only apple the last; Nitrogen utilization rate also varied sharply between plots, being the highest in the plot with Trifolium repens Linn, which was followed by the plot with Vulpia myuros C. and the plot with only apple in the end; In the plots interplanted with herbage ^15N residue was found mainly in the 0 - 20 cm soil layer, and higher in content than that in the 0 - 20 cm soil layer in the plot of apple only. However, the amount soil of residual ^15N in the 20 - 40 cm and 40 - 60 cm soil layers was the highest in the plot with apple only, which was followed by the plot with Lolium perenne L., and the plot with Trifolium repens Linn. in the end. In terms of nitrogen loss rate, the four plots displayed an order of apple only 〉 Lolium perenne L. 〉 Vulpia myuros C. 〉 Trifolium repens Linn.. In short, all the findings indicate that planting Trifolium repens Linn., Vulpia myuros C. and Lolium perenne L. in apple orchards improves nitrogen utilization rate and consequently reduces nitrogen loss rate by a certain degree.